Cody Wilson, the 25-year-old University of Texas law student who founded Austin-based Defense Distributed, told the BBC that he understands that 3D-printed guns could be used to hurt people but said: "I don't think that's a reason to not do it -- or a reason not to put it out there."

Defense Distributed's site also offered up blueprints for nine other 3D-printable firearms components, including a 30-round magazine and the lower receiver for an AR-15 assault rifle, the semi-automatic civilian model of the U.S. military's M16 rifle.

Wilson told Forbes he received a letter from the State Department Office of Defense Trade Controls Compliance demanding that he take down the online "Liberator" handgun.